There used to be a joke floating around the Internet. It was PDF file entitled the "Complete Book of Steve Jobs' Philanthropy," and when you clicked the file, it was just a bunch of blank pages.

Some close to Jobs said he was quite generous, but preferred to give quietly. Corporate philanthropy, however, can't really be done secretly; consistent with Jobs' belief that philanthropy is a personal, private matter, Apple didn't really engage in much corporate giving when it was under his control.

In fact, when he returned as CEO of Apple in 1997, more than a decade after being forced out of the top position, Jobs eliminated all corporate giving programs, a move based on his belief that expanding Apple would have done more good than giving money to charity. He did, however, get the organization involved with (RED) in 2006, and signed on as one of Stanford's corporate partners in an effort to build a new $2 billion hospital just before stepping down in 2011. So far, Apple has contributed $50 million.

Tim Cook sees philanthropy very differently, both personally and as a corporate leader. In early 2012, Cook announced that he had given $100 million to charity. And immediately after assuming the role of CEO, Cook announced that the company would start matching its employees charitable donations, up to $10,000. In just three years, Apple's contributions through its matching gifts program reached $50 million, which prompted the company to announce in October that it would expand the program to all countries where it has a presence. And as part of a program that is uniquely Apple, the nonprofits for which its employees volunteer will also receive donations, at a rate of $25 per hour. Assuming Apple's employees volunteer at roughly the same rate as Google's, that's about 150,000 volunteer hours, and $3.75 million in donations.

In addition, Apple was one of nearly 20 tech companies to answer the call when Tipping Point Community issued its SF Gives challenge earlier this year, raising $10 million from corporate sponsors for anti-poverty initiatives.

The latest news about Apple's newfound charitable side comes from Cook's holiday letter to his employees, in which he notes that the company has raised a record $20 million to fight AIDS in Africa this year, and more than $100 million since becoming involved with (RED) in 2006, making Apple (RED)'s largest corporate partner.

That would have been hard to imagine a few years ago.

It's worth noting that Apple has stepped up a charitable push over the past three years at the same time that the company has endured some of its worst publicity ever. First, there was a series of damning New York Times articles about terrible conditions for workers in the company's supply chain. Then there were the revelations that Apple was engaged in aggressive tax avoidance through offshore subsidiaries. Finally, the company came under legal investigation for colluding with other Silicon Valley employers to reduce competition (and thus repress wages) for top tech talent.

Sounds like a good period to ramp up Apple philanthropy, don't you think? On the other hand, Cook's done something he likely would have done under any conditions: He's brought Apple into the mainstream of corporate philanthropy, where it should have been all along.